Vowel reduction and merger in Pacific Northwest English.

The assumption stands in acoustic phonetics that vowel reduction (including undershoot and centralization of short vowels) is greater in casual than controlled speech. However, few studies have investigated the relative magnitude of language‐general (phonetic) effects relative to dialect‐specific (sociolinguistic) ones. This paper investigates reduction in vowels undergoing sound‐change. Pacific Northwestern English (PNWE) /ae/, /e/ are rising to the spectral location of /ey/, a “merger by approximation” [W. Labov, Princ. Ling. Change, Blackwell (1994)]. Sociolinguistic literature guided selection of two stable/changing pairs (in which one member is stable, the other involved in the merger): /iy ey/, /ɪe/. The normalized corpus (n=1500) was balanced for the following place and voicing and included three conditions (wordlist, reading, and casual). Speakers were partitioned into groups (merged/unmerged). Wassink’s [J. Acoust. Soc. Am. 119, 2334–2350 (2006)] spectral overlap assessment metric was used to dete...